package com.huan.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

/*
 * 作者： 王鹏欢
 * @Description 操作数据库工具类
 */
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    //静态代码块，类加载的时候就初始化了
    static {
        Properties properties = new Properties();
        //通过类加载读取对应的资源
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        try {
            //加载资源
            properties.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        //获取各个属性
        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");
    }

    //获取数据库的连接
    public static Connection getConnection() {
        Connection connection = null;
        try {
            //加载驱动
            Class.forName(driver);
            //使用地址、用户、密码连接数据库
            connection = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }

    //编写查询公共类
    public static ResultSet execute(Connection connection, PreparedStatement preparedStatement, ResultSet resultSet ,String sql, Object[] params) throws SQLException {
        //预编译
        preparedStatement = connection.prepareStatement(sql);
        //setObject，占位符从1开始，但是我们的数组是从0开始
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i + 1, params[i]);
        }
        //预编译不需要传SQL
        //查询结果获取结果集
        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }

    //编写增删改公共方法
    public static int execute(Connection connection,  PreparedStatement preparedStatement,String sql, Object[] params) throws SQLException {
        //预编译
        preparedStatement = connection.prepareStatement(sql);
        //setObject，占位符从1开始，但是我们的数组是从0开始
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i + 1, params[i]);
        }
        //返回执行更新的行
        return  preparedStatement.executeUpdate();
    }

    //释放资源
    public static boolean closeResource(Connection connection,  PreparedStatement preparedStatement,ResultSet resultSet) {
        boolean flag = true;
        if (resultSet != null) {
            try {
                resultSet.close();
                //GC回收
                resultSet = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }
            if (preparedStatement != null) {
                try {
                    preparedStatement.close();
                    //GC回收
                    preparedStatement = null;
                } catch (SQLException e) {
                    e.printStackTrace();
                    flag = false;
                }
            }
                if (connection != null) {
                    try {
                        connection.close();
                        //GC回收
                        connection = null;
                    } catch (SQLException e) {
                        e.printStackTrace();
                        flag = false;
                    }
                }
                return flag;
            }
        }
